Fan and manufacturing method thereof

ABSTRACT

A fan includes a motor base, a bearing, an impeller, a stator and a magnetic element. The motor base has a bearing stand in a center portion thereof. The bearing is accommodated within the bearing stand. The impeller includes a metallic case, a hub, plural blades and a rotating shaft. The metallic case has a top surface and a sidewall. The hub is sheathed around the metallic case. The blades are disposed around an outer periphery of the hub. The rotating shaft is protruded from a center portion of the top surface and penetrated through the bearing stand, wherein no raised ring structure is formed in the top surface of the metallic case, and the rotating shaft and the metallic case are jointed together by a laser welding process. The magnetic element is disposed on an inner wall of the metallic case and aligned with the stator.

FIELD OF THE INVENTION

The present invention relates to a fan, and more particularly to aslim-type fan. The present invention also relates to a method ofmanufacturing such a fan.

BACKGROUND OF THE INVENTION

With rapid development of high-tech industries, various electronicdevices such as computer or servers become essential in our lives. Asknown, the heat-dissipating efficacy of the electronic device influencesthe operating stability and the use life of the overall system. Forincreasing the heat-dissipating efficacy and the operating stability ofthe electronic device, a fan is usually installed within the electronicdevice or installed in the ambient environment to cool the electronicdevice. Typically, a conventional fan comprises an impeller and a motor.FIG. 1A is a schematic perspective view illustrating an impeller of aconventional fan. FIG. 1B is a schematic exploded view illustrating theimpeller of FIG. 1A. FIG. 1C is a schematic cross-sectional viewillustrating the impeller of FIG. 1A. Please refer to FIGS. 1A, 1B and1C. The impeller 1 comprises a hub 10, plural blades 11, a metallic ring12 and a rotating shaft 13. The blades 11 are disposed around the outerperiphery of the hub 10. The blades 11 and the hub 10 are integrallyformed by a plastic injection molding process. The metallic ring 12 isdisposed on the inner peripheral of the hub 10. The rotating shaft 13 isprotruded from a center portion of the hub 10.

For manufacturing the impeller 1, after the metallic ring 12 is placedwithin a plastic injection mold (not shown) and the rotating shaft 13 isinserted into the mold, the impeller 1 including the hub 10, the blades11, the metallic ring 12 and the rotating shaft 13 is produced by theplastic injection molding process. For increasing the adhesion betweenthe rotating shaft 13 and the hub 10, the thickness of the hub 10 shouldbe greater than a minimum thickness. In addition, a raised ringstructure 101 is vertically formed on the center portion of the innersurface of the hub 10 and extended along the direction of the rotatingshaft 13. The rotating shaft 13 is inserted into the raised ringstructure 101. Moreover, plural reinforcing ribs 102 are radiallyarranged around the raised ring structure 101. The rotating shaft 13further has an embossed recess 131 corresponding to the raised ringstructure 101 in order to further increase the adhesion between therotating shaft 13 and the hub 10.

The conventional impeller, however, still has some drawbacks. Forexample, since the thickness of the hub 10 should be greater than aminimum thickness and the raised ring structure 101 and the reinforcingribs 102 of the hub 10 are necessary, the process of producing the moldfor the impeller is difficult. In addition, the overall height of theimpeller is too high. Moreover, since the rotating shaft 13 further hasan embossed recess 131 to increase the adhesion between the rotatingshaft 13 and the hub 10, if a small-sized rotating shaft 13 is used toproduce a slim impeller, it is difficult to produce the embossed recess131.

Therefore, there is a need of providing a slim-type fan and amanufacturing method thereof in order to obviate the drawbacksencountered from the prior art.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a fan and amanufacturing method thereof so as to simplify the mold for theimpeller, avoid the problem of abrading the rotating shaft and simplythe process of producing the rotating shaft.

It is another object of the present invention to provide a fan and amanufacturing method thereof so as to reduce an overall thickness of thefan and achieve the slimness of the fan.

In accordance with an aspect of the present invention, there is provideda fan. The fan includes a motor base, a bearing, an impeller, a statorand a magnetic element. The motor base has a bearing stand in a centerportion thereof. The bearing is accommodated within the bearing stand.The impeller includes a metallic case, a hub, plural blades and arotating shaft. The metallic case has a top surface and a sidewallextended axially from an outer periphery of the top surface. The hub issheathed around the metallic case. The blades are disposed around anouter periphery of the hub. The rotating shaft is protruded from acenter portion of the top surface and penetrated through the bearingstand. In addition, no raised ring structure is formed in the topsurface of the metallic case, and the rotating shaft and the metalliccase are jointed together by a laser welding process. The stator isdisposed around an outer periphery of the bearing stand. The magneticelement is disposed on an inner wall of the metallic case and alignedwith the stator.

In an embodiment, the top surface of the metallic case has a thicknessof 0.1˜2.0 mm. No embossed recess is formed in the rotating shaft. Theoverall thickness of the fan is smaller than 10 mm.

In accordance with another aspect of the present invention, there isprovided a fan. The fan includes a motor base, a bearing, an impeller, astator and a magnetic element. The motor base has a bearing stand in acenter portion thereof. The bearing is accommodated within the bearingstand. The impeller includes a metallic case, plural blades and arotating shaft. The metallic case has a top surface and a sidewallextended axially from an outer periphery of the top surface. The bladesare disposed around an outer periphery of the metallic case. Therotating shaft is protruded from a center portion of the top surface andpenetrated through the bearing stand. In addition, no raised ringstructure is formed in the top surface of the metallic case, and therotating shaft and the metallic case are jointed together by a laserwelding process. The stator is disposed around an outer periphery of thebearing stand. The magnetic element is disposed on an inner wall of themetallic case and aligned with the stator.

In an embodiment, the blades are made of metallic material. The bladesare integrally formed with the metallic case.

In accordance with a further aspect of the present invention, there isprovided a method for manufacturing a fan. The method comprises stepsof: providing a metallic case having a top surface and a sidewallextended downwardly from an outer periphery of the top surface;combining a rotating shaft with the metallic case by a laser weldingprocess, so that the rotating shaft is protruded from a center portionof the top surface of the metallic case; placing a combination of therotating shaft and the metallic case within a mold, and producing a huband plural blades by a plastic injection molding process, wherein thehub is sheathed around the metallic case, and the blades are disposedaround an outer periphery of the hub; providing a motor base having abearing stand in a center portion thereof, and accommodating a bearingwithin the bearing stand, and disposing a stator around an outerperiphery of the bearing stand; and disposing a magnetic element on aninner wall of the metallic case, and penetrating the rotating shaftthrough the bearing such that the magnetic element is aligned with thestator.

The above contents of the present invention will become more readilyapparent to those ordinarily skilled in the art after reviewing thefollowing detailed description and accompanying drawings, in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a schematic perspective view illustrating an impeller of aconventional fan;

FIG. 1B is a schematic exploded view illustrating the impeller of FIG.1A;

FIG. 1C is a schematic cross-sectional view illustrating the impeller ofFIG. 1A;

FIG. 2A is a schematic perspective view illustrating an impeller of afan according to an embodiment of the present invention;

FIG. 2B is a schematic exploded view illustrating the impeller of FIG.2A;

FIG. 2C is a schematic cross-sectional view illustrating the impeller ofFIG. 2A;

FIG. 3 is a schematic cross-sectional view illustrating a fan accordingto an embodiment of the present invention; and

FIG. 4 is a schematic cross-sectional view illustrating a fan accordingto another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention will now be described more specifically withreference to the following embodiments. It is to be noted that thefollowing descriptions of preferred embodiments of this invention arepresented herein for purpose of illustration and description only. It isnot intended to be exhaustive or to be limited to the precise formdisclosed.

FIG. 2A is a schematic perspective view illustrating an impeller of afan according to an embodiment of the present invention. FIG. 2B is aschematic exploded view illustrating the impeller of FIG. 2A. FIG. 2C isa schematic cross-sectional view illustrating the impeller of FIG. 2A.Please refer to FIGS. 2A, 2B and 2C. The impeller 2 comprises a hub 20,plural blades 21, a metallic case 22 and a rotating shaft 23. Themetallic case 22 is sheathed by the hub 20. The blades 21 are disposedaround the outer periphery of the hub 20. In addition, the blades 21 andthe hub 20 are integrally formed by a plastic injection molding process.

The metallic case 22 has a top surface 221 and a sidewall 222. Thesidewall 222 is axially or downwardly extended from the outer peripheryof the top surface 221. The rotating shaft 23 is made of metallicmaterial, and protruded from a center portion of the top surface 221. Anopening is formed in the center portion of the top surface 221 of themetallic case 22. After the rotating shaft 23 is inserted into theopening, the rotating shaft 23 is combined with the top surface 221 ofthe metallic case 22 by a laser welding process. In FIG. 2C, the weldingregion S is circled by a dashed line. During the laser welding processis performed, high power laser beams are projected on the metallicsurface to melt the metallic surface. After the molten metal is cooled,the rotating shaft 23 and the metallic case 22 are jointed together.Since the laser welding process has small welding joints, high precisionand centralized energy, the laser welding process is able to form asecure welded structure through thin-walled parts. Since the laserwelding process may create a strong adhesion between the rotating shaft23 and the metallic case 22, the raised ring structure of the hub andthe embossed recess of the rotating shaft that are used in theconventional impeller may be omitted. Moreover, since the thickness ofthe top surface 221 of the metallic case 22 is too small (e.g. 0.1˜2.0mm), it is advantageous to design a slim-type fan by using the impeller2. As the thickness of the metallic case 22 is decreased, the spaceunder the metallic case 22 for accommodating the stator of the fan willbe increased. In this situation, the coil turn may be increased in orderto enhance the operating performance of the fan.

For manufacturing the impeller 2, the rotating shaft 23 and the metalliccase 22 are firstly jointed together by the laser welding process, thenthe combination of the rotating shaft 23 and the metallic case 22 isplaced within a plastic injection mold (not shown), and finally the hub20 and the blades 21 of the impeller 2 are produced by the plasticinjection molding process. In accordance with the present invention, noraised ring structure is formed in the top surface 221 of the metalliccase 22, and no embossed recess is formed in the rotating shaft 23. Inaddition, the thickness of the top surface 221 of the metallic case 22is ranged from 0.1 to 2.0 mm.

Since the rotating shaft 23 and the metallic case 22 are firstly jointedtogether by the laser welding process and then the hub 20 and the blades21 of the impeller 2 are produced by the plastic injection moldingprocess, the mold for the impeller 2 of the present invention is simplerthan the mold used in the conventional impeller. In addition, theadhesion between the rotating shaft and the hub is not necessarily takeninto consideration, the possibility of abrading the rotating isminimized, the thicknesses of the hub and the metallic case are notneeded to be greater than the minimum thickness, and the hub and themetallic case are not shrunk or deformed after the plastic injectionmolding process is done. Moreover, since no embossed recess is formed inthe rotating shaft, the process of producing the rotating shaft is verysimple. Since the welding points for performing the laser weldingprocess are symmetrically arranged or arranged in a ring-shaped profile,the range of the torsion force of the rotating shaft will be widened.

The laser welding process may be performed to weld various metals. Thatis, the metallic case 22 and the rotating shaft 23 of the impeller 2 maybe made of any metallic material or alloy, for example gold, silver,copper, iron, titanium, nickel, tin, aluminum, chromium, or the alloythereof. In addition, the metallic case 22 and the rotating shaft 23 maybe made of identical material or different materials.

Please refer to FIG. 2C. The outer surface of the metallic case 22 mayhas a level difference. That is, the metallic case 22 further comprisesa sub-top surface 223, whose horizontal level is slightly lower than thetop surface 221. When the metallic case 22 is sheathed by the hub 20,the sub-top surface 223 of the metallic case 22 is sheltered by the hub20, but the top surface 221 of the metallic case 22 and the hub 20 aresubstantially at the same level. As a consequence, the overall height ofthe fan is not considerably increased.

FIG. 3 is a schematic cross-sectional view illustrating a fan having theimpeller of FIGS. 2A-2C according to an embodiment of the presentinvention. As shown in FIG. 3, the fan 3 comprises a hub 30, pluralblades 31, a metallic case 32, a rotating shaft 33, a motor base 34, abearing 35, a stator 36, a magnetic element 37 and a fan frame 38. Themetallic case 32 is sheathed by the hub 30. The blades 31 are disposedaround the outer periphery of the hub 30. In addition, the blades 31 andthe hub 30 are integrally formed by a plastic injection molding process.The metallic case 32 is an integral part, and comprises a top surface321 and a sidewall 322. The sidewall 322 is axially or downwardlyextended from the outer periphery of the top surface 321. The rotatingshaft 33 is made of metallic material, and protruded from a centerportion of the top surface 321. The rotating shaft 33 is combined withthe top surface 321 of the metallic case 32 by a laser welding process.A bearing stand 341 is formed in a center portion of the motor base 34.The bearing 35 is accommodated within the bearing stand 341. Therotating shaft 33 is penetrated through the bearing 35. The stator 36 isdisposed around the outer periphery of the bearing stand 341. Themagnetic element 37 is disposed on the inner wall of the metallic case32 and aligned with the stator 36. The fan frame 38 is disposed at theouter portion of the fan 3 and surrounds the hub 30, the blades 31, themetallic case 32, the rotating shaft 33, the motor base 34, the bearing35, the stator 36 and the magnetic element 37. Since the rotating shaft33 and the metallic case 32 are jointed together by the laser weldingprocess, the thicknesses of the metallic case 32 is not needed to begreater than the minimum thickness. In this situation, the overallthickness H of the fan 3 may be smaller than 10 mm. Preferably, theoverall thickness H of the fan 3 is smaller than 7 mm. Consequently,this slim-type fan 3 is achievable and may be used in an ultra-thinnotebook computer or other slim-type electronic device.

The present invention further provides a method of manufacturing a fan.Firstly, the rotating shaft 33 and the metallic case 32 are firstlyjointed together by a laser welding process. Then, the combination ofthe rotating shaft 33 and the metallic case 32 is placed within aplastic injection mold (not shown). Afterward, the hub 30 and the blades31 of an impeller are produced by the plastic injection molding process.In accordance with the present invention, no raised ring structure isformed in the top surface 321 of the metallic case 32, and no embossedrecess is formed in the rotating shaft 33. In addition, the thickness ofthe top surface 321 of the metallic case 32 is ranged from 0.1 to 2.0mm. Then, a motor base 34 is provided, wherein the motor base 34 has abearing stand 341 in a center portion thereof. Afterward, a bearing 35is accommodated within the bearing stand 341, and a stator 36 isdisposed around the outer periphery of the bearing stand 341. Then, amagnetic element 37 is disposed on the inner wall of the metallic case32. Thereafter, the rotating shaft 33 is penetrated through the bearing35 such that the magnetic element 37 is aligned with the stator 36.Then, a fan frame 38 is disposed at the outer portion of the aboveresulting structure. Meanwhile, the fan 3 is assembled.

FIG. 4 is a schematic cross-sectional view illustrating a fan accordingto another embodiment of the present invention. As shown in FIG. 4, thefan 4 comprises plural blades 41, a metallic case 42, a rotating shaft43, a motor base 44, a bearing stand 441, a bearing 45, a stator 46, amagnetic element 47 and a fan frame 48. In this embodiment, the blades41 are made of metallic material rather than plastic material. As aconsequence, the blades 41 are integrally formed with the metallic case42, and blades 41 are disposed around the outer periphery of themetallic case 42. In addition, no hub is included in the fan 4. Theconfigurations of the other components of the fan 4 are similar to thoseof the fan 3 as shown in FIG. 3, and are not redundantly describedherein. Since the rotating shaft 43 and the metallic case 42 are jointedtogether by the laser welding process, the thicknesses of the metalliccase 42 is not needed to be greater than the minimum thickness. In thissituation, the overall thickness H of the fan 4 may be smaller than 10mm. Preferably, the overall thickness H of the fan 4 is smaller than 7mm. Consequently, this slim-type fan 4 is achievable and may be used inan ultra-thin notebook computer or other slim-type electronic device

From the above description, the fan impeller of the present inventioncomprises a hub, plural blades, a metallic case and a rotating shaft.The rotating shaft is protruded from a center portion of the topsurface. The rotating shaft and the metallic case are directly jointedtogether by a laser welding process. In addition, no raised ringstructure is formed in the top surface of the metallic case. Inaccordance with the present invention, the top surface of the metalliccase has a thickness of 0.1˜2.0 mm. The problem of abrading the rotatingshaft will be eliminated. In addition, the mold for the impeller issimplified. Since no embossed recess is formed in the rotating shaft,the range of the torsion force of the rotating shaft will be widened.Moreover, since the overall thickness of the fan may be smaller than 10mm, the slim-type fan of the present invention may be used in anultra-thin notebook computer or other slim-type electronic device.

While the invention has been described in terms of what is presentlyconsidered to be the most practical and preferred embodiments, it is tobe understood that the invention needs not be limited to the disclosedembodiment. On the contrary, it is intended to cover variousmodifications and similar arrangements included within the spirit andscope of the appended claims which are to be accorded with the broadestinterpretation so as to encompass all such modifications and similarstructures.

What is claimed is:
 1. A fan, comprising: a motor base having a bearingstand in a center portion thereof; a bearing accommodated within saidbearing stand; an impeller comprising: a metallic case having a topsurface and a sidewall extended axially from an outer periphery of saidtop surface; a hub sheathed around said metallic case; plural bladesdisposed around an outer periphery of said hub; and a rotating shaftprotruded from a center portion of said top surface and penetratedthrough said bearing stand, wherein no raised ring structure is formedin said top surface of said metallic case, and said rotating shaft andsaid metallic case are jointed together by a laser welding process; astator disposed around an outer periphery of said bearing stand; and amagnetic element disposed on an inner wall of said metallic case andaligned with said stator.
 2. The fan according to claim 1 wherein saidtop surface of said metallic case has a thickness of 0.1˜2.0 mm.
 3. Thefan according to claim 1 wherein an opening is formed in said centerportion of said top surface of said metallic case, and said rotatingshaft is inserted into said opening.
 4. The fan according to claim 1wherein said rotating shaft is made of metallic shaft.
 5. The fanaccording to claim 1 wherein no embossed recess is formed in saidrotating shaft.
 6. The fan according to claim 1 wherein said blades areintegrally formed with said hub.
 7. The fan according to claim 1 whereinsaid metallic case further comprises a sub-top surface at a horizontallevel lower than said top surface, wherein when said metallic case issheathed by said hub, said sub-top surface of said metallic case issheltered by said hub.
 8. The fan according to claim 1 wherein said fanfurther comprises a fan frame, which is arranged at an outer portion ofsaid fan.
 9. The fan according to claim 1 wherein an overall thicknessof said fan is smaller than 10 mm.
 10. A fan, comprising: a motor basehaving a bearing stand in a center portion thereof; a bearingaccommodated within said bearing stand; an impeller comprising: ametallic case having a top surface and a sidewall extended axially froman outer periphery of said top surface; plural blades disposed around anouter periphery of said metallic case; and a rotating shaft protrudedfrom a center portion of said top surface and penetrated through saidbearing stand, wherein no raised ring structure is formed in said topsurface of said metallic case, and said rotating shaft and said metalliccase are jointed together by a laser welding process; a stator disposedaround an outer periphery of said bearing stand; and a magnetic elementdisposed on an inner wall of said metallic case and aligned with saidstator.
 11. The fan according to claim 10 wherein said blades are madeof metallic material.
 12. The fan according to claim 11 wherein saidblades are integrally formed with said metallic case.
 13. A method formanufacturing a fan, said method comprising steps of: providing ametallic case having a top surface and a sidewall extended downwardlyfrom an outer periphery of said top surface; combining a rotating shaftwith said metallic case by a laser welding process, so that saidrotating shaft is protruded from a center portion of said top surface ofsaid metallic case; placing a combination of said rotating shaft andsaid metallic case within a mold, and producing a hub and plural bladesby a plastic injection molding process, wherein said hub is sheathedaround said metallic case, and said blades are disposed around an outerperiphery of said hub; providing a motor base having a bearing stand ina center portion thereof, and accommodating a bearing within saidbearing stand, and disposing a stator around an outer periphery of saidbearing stand; and disposing a magnetic element on an inner wall of saidmetallic case, and penetrating said rotating shaft through said bearingsuch that said magnetic element is aligned with said stator.
 14. Themethod according to claim 13 wherein said laser welding process isperformed to joint the rotating shaft and said metallic case byarranging welding points in a ring-shaped profile.
 15. The methodaccording to claim 13 wherein said laser welding process is performed tojoint the rotating shaft and said metallic case by arranging weldingpoints symmetrically.